AB-INITIO CALCULATIONS OF IONIC AND HYDROGEN-BONDING INTERACTIONS WITH THE OCN-, SCN- AND SECN- ANIONS

Many studies have shown that ionic and hydrogen bond interactions affe ct the bonding and structure of the cyanate, thiocyanate and selenocya nide anions. These effects have been observed experimentally by pertur bations of the anions vibrational modes and have been interpreted in t erms of numerous solution species. In order to contribute to our under standing of the nature of the frequency shifts in these anions, ab ini tio calculations of a variety of ionic and hydrogen bonded complexes a re reported. There is good agreement between experimental vibrational frequencies in solution and the ab initio predictions. The perturbatio ns in the bond lengths and the vibrational modes by electrostatic inte ractions can be understood by changes primarily in the pi molecular or bitals. Visualization of the molecular electrostatic potential shows r emarkable differences in the polarization of these anions that depend on the nature of the electrostatic interaction.